Hesitation sometimes with trac control pic(car skid pic) appearing on dash..

Hello folks,
My 02 4runner had VSC & TRAC lights on with CEL..replaced the O2 sensor (before cat) & the lights are gone. But now sometimes while driving from a stop..it hesitates & same time i see the car skid (Traction control) icon appears on top left on dash. If i let go of gas pedal and press again..then its normal to drive. Its scary as when in traffic it just doesnt move..NO action while pressing pedal..but engine is not stalling..Could it be that CAT is clogged..?? cause the PO told me that the VSC & TRAC lights were on for almost 2 years or so and he just drove like that. Appreciate inputs. After swapping the O2 i just did a erase code with OBD tool..didnt disconnect battery.